The minimum amount for filing depends on your total gross income from all sources......after that the ratio of AZ-taxable income will eventually be used in the AZ tax calculation.
Thus if you are filing MFJ and earned $5k in AZ and $24k total Federal , then none of the AZ income will get taxed and you'll get a refund.
But if you earned $5k in AZ, but $30k or more total Federal....then that 5k will get taxed at some level....to be determined when you file next year. (might depend some on what other deductions you might have)
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The details on when an employer is "required" to withhold state taxes can vary..... I don't know AZ requirements, but I suspect the employer knows that as their employee, you are expected to earn over the minimum federal income such that the are required to withhold some AZ taxes. Since they operate in AZ, they would have to follow AZ tax rules.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
